Telephone-exchange system



March 10, 1925- J. F. DAHL TELEFHONE EXCHANGE SYSTEM Filed Dec. 30, 1922. 2 Sheets$heet l /n ven for: Jack E Dah/ Marh 10, 1925- J. F. DAHL TELEPHONEEXCHANGE SYSTEM Filed Dec. 30, 1922. 2 Sheets-Sheet 2' In vehfor': Jack, ffDah/ Nu a E.

Patented Main-10, 1925.

1 1,529,171, UNITED STATES PATENT FFlCE...

JACK F. DAHL, OF EAST ORANGE, NEW] JERSEY, ASSIGNOR TO ELIli1C 'lIR-IC COMPANY, INCORPORATED, OF NEW YORK, N. Y., ACORP ORATION OF NEW YORK TELEPHONE-EXCHANGE SYSTEM.

Application filed December 30, 1922. Serial nojeiooeo.

To (4% whom it may concern:

Be it known that I, JACK F. Danna citizen of the United States of America, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improveinents in Telephone-Exchange Systems, of which the following is a full, clear,'concise and exact description.

This invention relates to telephone exchange systems and more particularly to systems in which connecting operators are employed for extending connections inaccordance with line designations displayed before the operators by indicating mechanism.

In systems where certain offices are equipped with machine switching apparatus, whereas other oiiices employ manual operators for establishing connections, it" is found desirable that the mai'iual opeators be given information required for them to eXend or complete connections incoming from the machine switching oitice without the necessity During the transition period when an ex change area is being changed from a manual operating basis to a machine switching or semi-automatic basis, and prior to the time when a particular manual oflice is required to extend connections incoming from-other offices operating upon a machine switching basis, it is necessary that the call extending circuits or trunks of the manual ofiice be arranged to operate on a call wire basis. ,Vhen operating on a call wire basis, calls incoming to the manual oifice willoriginate in other manual offices and the originating operators will obtain trunk assignmentsin the usual manner over call wire circuits and will orally inform the operator in the terminating manual office of the desi'gnation-of the desired line; When, then,-the-tiine-arrives for cutting the originatingoflice, over to operate upon a machine switching basis, the circuits at theterm-inamngmanual oififce must be modified tofunction there-with upon a call indicator basis.

To accomplish this with a minimum of delay, the trunk circuits otthe manua l ofice are equipped,.. when installed, with apparatus for enabling themto-operate either-upon a call .wire basis orupon' a can man-ace basis and such apparatus, as for example, the indicating mechanismis strappedxout until such time as the circuits-are'required to operate upona call indicator *basis. At that time, the call indicatormechanism and the associated circuits are strapped into s'erv ice and such apparatus of the trunkcircuits as is used only when such circuits are operating as call wire circuits is strapped, out of service.

In some exchange areas, parties upon party lines are selectedsem-iselectiVely,that is, a single source of ringing current is employed and connected toeither the tip or the ring side of the called line, depending upon whether the bell ofth-edesired party is connected to the tip or to-the ring side of the line, and since on tour party lines, the bells of two of the partiesare, con nected between the tip side or the line and ground, and the bells otfth'e other two parties are connected between the ring side of the line and ground, selection between the two parties whose bells are connected to'the same side of the line is'turther made by manual application of the ringing currentaccording to a ringing code. If the exchange is equipped with standard indicator mechanism, which is designed to auto line.

be to call a desired party on a party More specifically, it is an object of this invention to provide means for selectively preparing circuitsfor the application of ringing current to either side of a party line and to indicate to the operator the manner in whichthe ringing current is to be then applied for calling one of four partiesv of a party line.

. These ob ects are accomplished by providing a pair of ringing selection relays which may be variously operated by a group of master ringingkeys during the period that the trunk circuits are OPBIatGd IIPOII a call I wire basis or automatically by call indicator mechanism, when the trunk circuits: have been cutover to operate upon a call indicator basis, to selectively prepare circuits for associating a ringing current source with either the tip or the ring side of a called line and to light a lamp steadily or intermittently for indicating which party of the two whose bells are connected to the same side of the line is to be called inresponse to ringing codes manually determinedb-y the'operator. 1 I

Other features of the invention not specificallyreferred to above will clearly appear from the following description and 1 claims.

Figs. 1 and 2 of the drawings when'arranged with Fig. 2 at the right of Fig. 1

v diagrammatically represent such portions of a telephone'exchange system are are neces- I sary to embody the present invention. Fig.

1 shows. a calling subscribers line A terini mating in a "machine switching office X of fan exchange system and having access through a line switch, district selector and office selector to a trunk circuit at a terminating operators position of a manual In addition, Fig. 1 shows in the portion thereof, such portions' of a ofiice. lower call in to an understanding of thisinvention. Fig.

2 shows a trunk circuit ata terminating operators (position of a manual office which is arrange for initial operation on a call wire basis and for ultimate operation on a call indicator basis, together with a party. line terminating in such, oflice.

closure of this invention.

Stearriand F. J. Scudder, No. 1,395,977,-

In, the system herein disclosed, the appa' ratus at the originating machine switching oli'ice X, comprising the line switch 100, district selector 150, office selector 175, and sender 105 has been indicated'very briefly as it enters only incidentally into the dis- For a full dis closure ofapparatus. of this character, reference may be had to the patent to F. A.

issued November 1,1921, or to the patent to F. A. Stearn No. 1,505,171. The cord circuit at the operators position 0 of Fig.

'1 is of the usual manual type and indicates desired.

icator mechanism as are necessary one of the cord circuits of the oflice X in use prior to its cut-over from manual operationv to machine switching operation.

The trunk circuit and indicating mechanism of Figs. 1 and 2 are 'ofsubstantially the same type as disclosed in the patent to A. E. Lundell andE. Clark, No. 1,464,084, being modified, however, to selectively control the selection of ringing. current insubstantially the manner disclosed inthe patent to A. E. Lundell, N 0. 1,312,791,

issued August 12, 1919. In addition, and in accordance with this invention, the trunk circuit of F 2is further modified to permit an indication to the operator of the manner in which she must apply ringing current to the called line to call the party Inasmuch as the trunk circuit of Fig. 2 has been disclosed as provided with apparatus for initially operating it upon a call wirebasis and for ultimately operating it upon a call indicator basis, straps 111, 112, 205 to 215 inclusive shown in. full lines. and straps 200 to .204 247 and 24:8 shown in dotted lines have been provided for con verting the trunk circuit. With the straps shown in full lines inserted, and the straps shown in dotted lines removed, the trunk circuit functions on a' manual call wire basis in conjunction with originating manual operators positions such as-position O of office I connection between them for example, would be accomplished at the time of the cut-over by a niulti-terminal plug or the equivalent thereof.

The called line shown at the right of Fig.

2 has been disclosed with but one of the four substations thereof shown in full, the bell circuits only of the remaining three substations C, D and E being disclosed. It is to r be understood, however, that each of the'sub- I stations is similar to the substation B with the exception of the mannerin which the bell circuits are connected. It will be noted that stations B and D are disclosed with. their bells connected between the tip side 243 of the line and ground and that stations C and E are disclosed with their bells connected between the ring side 24A of the line and ground.

Having now briefly described the apparatus employed in carrying out the objects of this invention and the general manner in which it functions, the invention w ll now be described-more n detail. First, .a description will be given of the apparatus as it functions when operating upon a call wire basis with the straps shown in full lines inserted and the straps in dotted lines removed. The invention -will then be described as it functions after the trunk circuit has been changed over to operate upon a call indicator basis. 1

Connection extended on call wire basis-- it willbe assumed that a subscriber in the otiice X desires a connection with the substation B on a line terminating in the office Y, the designation of which line is'3578-l i and that this connection is to be established wholly by manual means. The subscriber in the ofiice X will in the usual manner initiate the call and obtain a connection with the op erator at position .6 who, upon ascertaining that the calling subscriber desires a connection with a subscriber whose line terminates iu'the office Y, will obtain the assignment of a trunk circuit extending between ofhces X and Y from the operator at position 0 of the office Y. T his assignment is obtained over a call wire circuit (not shown) extending between the offices. Having obtained the assi nment, the operator at position O will then forward designation of the desired line to the operator'in O over the call wire circuit.

The operator at position 0 having assigned a trunk circuit to the use of the operator at position 0, which trunk circuit will be assumed to be the one disclosed tern'iinating in the jack 142 at position 0, will de press the assignn'ient key 217 of this trunk circuit. lVith the key 217 depressed, a circuit is established for the relay 220 which may be traced from ground, strap 210, contact of key-217, strap 212, the normal contacts associated with theout-er left armature of relay 218, the inner right armature and back contact of relay 219, the winding of relay to battery at the outer right armature and Contact of relay 221. Relay 220 energizes in this circuit closing a locking circuit for itself from ground through the contact of key 217, thence, as traced through the winding of relay 220 to battery through the inner right armature and front contact of relay 220. Relay 220 also closes a circuit for the assignment lamp 222 which may be traced from ground through the outer right armature and front contact of relay 220, lamp 222, to battery through the outer left armature and front contact of relay 220. If plug .231 is not at this time inserted in 282 an additional battery supply for lamp 222 obtained at the intermediate armature and back contact of sleeve relay 224i. suining. however, that the plug 281 is down. a circuit is now established for relay 223 which may be traced from battery through the strap 213, the lower armature and back contact of sleeve relay 224, right winding of relay 223, inner left armature and front contact of relay 220, contact of key 217, strap 210 to ground. Relay 223 now energizes closing a locking circuit for itself from ground through its inner left armature and front contact, through both of its windings, lower armature and back contact of relay 224i, strap 213 to battery. I

With relay 223 energized, acircuit is now established for relay 221 which may be traced from battery through the winding of relay 221 to ground at the right armature and front contact of relay 223. Relay221 upon energizing, opens the initial energizing circuit of relay 220 at its outer right armature and contact and at its outer left armature and front contact connects the interrupter 226 to the back contact of the outer right armature of relay 220 preparat'oryzto flashing the lamp as hereinafter described. Relay 221 also establishesa circuit for relay 218 which may be traced from ground through the winding of relay218, the inner right arniiature and front contact of relay 221,to battery through the inner right armature and front contact of'relay 220. Relay 218 upon energizing, closes a locking circuit for itself extending through its winding, its out-er right armature and front contact to battery through the winding of relay 219. Relay 219, however,.does not operate in this locking circuit since its winding is shunted by battery connected through the inner right armatureand con tact of relay 220.

With relays 218 and 223 energized, a cir cuit is now established for relay 225 which l lll may be traced from ground, strap 215, the

ou left armature and contact of relay 23.. winding of relay 225 to battery through the inner left armature and contact of relay 218. As soon as relay 218 operates, the holding circuit for relay 220 is opened at the break contacts associated with the outer left armature of relay 218 and relay 220 thereupon deenergizes, opening the shunt around the winding of relay 219 .to permit the operation of the latter relay. With relay 220 deenergized, a circuit is now effective for flashing the assignment lamp 222, which circuit may be traced from ground through the interrupter 226, the outer left armature and front contact of relay 221, the outer right armature and back contact of relay 220, lamp 222 to battery through the intermediate armature and back contact of sleeve relay 224. The operator noting the flashing v of lamp 222 is apprised of the fact that relay 225 is operated and that the master ringing keys 250 are now associated with the trunk circuit which she has assigned.

Theoperator now depresses a master ringing key of the group 250 corresponding to the party upon the party line with whom the connection is desired. In the caseassumed, she depresses the key 252 corresponding to the party W. With key 252 destrap 208, conductor 228, lower spring and contact of key. 252, to ground. Relays 229 and 230 upon energizing look over their left armatu'res and front contacts thereof to ground at the outer left armature and frontcontact of relay 219. p The operation of relay. 229 determines the side of the line to which current from the source 241 is to be applied and relay 230 determines the manner in which this current is to be applied by the operator. I The operation ofrelay 225 disconnectsthe tip and ring conductors 255 and 256 of the trunk circuit from the windings of relay 238 so that'should the operator at position 0 insertthe plug 141 of her cord circuit in the jack 142, of the trunk circuit, relay 238 will not operate, and consequently the relay 240 will not operate to shunt downrelay '218 and to open the circuit of relay 225 before the operator at position 0 has had time to operate a master ringing key.

The operator at position 0 having depressed the master ringing key 252, now tests the jack of the desired line to ascertain ifit is busy or idle and if found to be idle extends connection to such line by inserting the plug 231 in the jack 232. With the plug 231 inserted in the Jack 232, .a circuit is established for the sleeve relay 224 extend ing from battery through the winding of this relay to ground through the sleeve of plug 231 and the sleeve of jack 232. Relay 224 upon operating disconnects the tip of the plug from the test conductor 235 leading to the operators telephone set and connects the tip of the, plug withthe tip strand of the trunk circuit. At its lowermost armature, relay 224 opens the locking circuit of relay 223, which in turn opens the circuits of relays 221 and 225. With relay 221 de energized, the interrupter 226 is disconnected from the circuit through lamp 222 an'd lamp 222 is thereupon extinguished.

A circuit is now effective for the ringing lamp 236 which may be traced from battery through the intermediate armature and front contact of relay 224, left armature and back contact of relay 237, lamp 236, the right armature and front contact of relay-230 to ground through the interrupter 226. The lamp 236 now flashes indicating to the'operator that she should apply ringing current through the operation of key 234 in accordance with a code for ringing the operatorat position 0 has connected 7 with the trunk circuit, relay 238 operates over a circuit which may be traced from battery, ring of plug 141, ring of jack 142, strap 112, conductor-256, innermost lower armature and back, contact of relay 225,'

lower left winding of repeating coil 251, right armature and back contact of relay 253, strap 206, low resistance right winding of relay 238, high resistance left winding of relay 238, strap 205, left armature and back contact of relay 253, upper left winding of repeatingcoil251, upper armature and back contact of relay 225, conductor strap 111, tip of jack 142, tip of plug 141 to ground at the cord circuit atpos'ition 0. Relay 238, upon operating, closes an obvious circuit for relayn240'which in turn closesa shunt around the winding of relay 218. This shunt may be traced from ground through the winding of relay 218,

the outerright armature and front contact of relay 218, the inner left armature and front contact of relay 219, the armature and contact of relay 240, strap 209 to ground at the right armature and backcontact of relay 223. Relay 218 now deenergizes, relay 219 being maintained over the circuit just traced to ground at the back contact and right armature of relay223 under the control of line relay 238. I 7

Upon. the operation of key 234, a circuit is established for ringing relay 233 which may be traced from battery throughthe intermediate armature and front contact of sleeve relay 224, the outer right armature and contact of relay 219, winding of relay contacts of key 234, normal contacts associated with the outer right arn'xature of relay 218, the inner left armature, and front contact of relay 219, the armature and con tact of relay 240, strap 209, to ground at the right armature and back contact of relay Upon each energization of ringing relay 233 in response to the operation of'key 234,

it being assumed that to call party W at substation B, a ringing code of two long I impulses is employed, with relay 2291energized as assumed,'ringing current from the source 241 is connected over the outer left armature and front contact of relay 229, the upper armature and front contact of re lay 233, the upper armature and front contact of sleeve relay 224, tip of plug 231, tip

of jack 232, line conductor 243, to ground through the bell 242 at substation B. At the same time, the ring conductor 244 of the called line is connected to ground over the ring of jack 232, ring of plug 231 ,lower armature and front contact of ringing relay 233 and the right armature and front contact of relay 229. v

The subscriber B in response to two long rings, removes his receiver from its switchhook, thereupon closing a circuit for the supervisory relay 239 as soon as the ringing key 234 is released. The circuit for relay 239 may be traced from battery, lower right winding of repeating coil 251, relay 239, lower armature and back contact of relay 233, ring of plug 231, ring of jack 232, conductor 244, thence through the substation B returning over conductor 243, tip of jack 232, tip of plug 231, upper armature and front contact of relay 224, upper armature and back contact of relay 233 to ground through the upper right winding of repeat-- ing coil 251. Relay 239, upon energizing, closes an obvious circuit for relay 249 which in turn, closes an obvious circuit for relay 253 and a circuit for relay 237. The circuit of relay 237 extends from ground through the intermediate armature and contact of relay 249, the break contacts of the right armature of relay 237, winding of this relay, intermediate armature and front contact of relay 224 to battery. Relay 23'? u on operating locks directly to ground through the make contact of its right armature, and at its left armature and contact opens the circuit of ringing lamp 236, which hereupon extinguished.

Relay 253 upon energizing, with relay 249 energized, reverses the connection of the windings of relay 238 with the circuit eX- tending back to the cord circuit at position 0, and relay 249 closes a shunt around the left high resistance winding of relay 238. Relay 238 is now maintained energized over a circuit which may be traced from ground through the upper right Winding of the repeating coil at position 0, tip of plug 141, tip of jack 142, conductor 255, upper armature and back contact of relay 225, upper left winding of repeating coil 251, right armature and front contact of relay 253, strap relay 23S, outer right armature and front contact of relay 249, strap 205, left armature and front contact of relay 253, lower left winding of repeating coil 251, innermost lower armature and back contact of relay 225, conductor 256, ring of jack 142, ring of plug 141 to battery at the cord circuit at position 0. With the high resistance winding of relay 238 shunted, the supervisory relay at the cord circuit of position operates to indicate to the operator that the called subscriber has responded.

206, right low resistance winding of' Upon the termination of the conversa- I tion, between the subscriber in the office and the subscriber Bin the oflice Y, the operator at position 0 will receive the usual 3 disconnect signal, the calling supervisory Upon the ClBGIIETglZfi/UOIL of relay 240, the holding circuit of relay 219 "is opened whereupon a circuit is established for the disconnect lamp. 245 which may be traced from battery through the intermediate armature and front contact of relay 224, disconnect lamp 245 to ground at the outer left armature and back contact of relay 219. The operator at position 0 in response to the lighting of this lamp removes-the plug 231 from the jack 232 thereupon opening the circuit'of sleeverelay 224, thereby opening the circuit of lamp 245 and causing it to become extinguished. Since upon the I signal being operated by the removal of the i deenergization of relay 219, the locking circuits of relays 229 and 230 were opened, and upon the deenergizationfof relay 224, the holding circuit of relay 237 is opened, all

apparatus employed in the connection s now in its normal position. Conversion of trunk czrcmt for operation upon relay call indicator ba sz's.-W hen itthe establishment of becomes necessary'to convert the trunk circuit shown in Fig. 2 foroperation upon a. call indicator basis, following the cut-over of the office X from a manual basis to a machine switching basis, straps 111, 112, 205

to 215, inclusive are removed and the straps 200 to 204 inclusive, 257, 258, 247 and 248 are inserted. Connections from subscribers lines terminating in the oflice' X are thereafter established with subscribers lines terminating in the office -Y upon a semimechanical basis.

The subscriber A whose line terminates in the olflce X, desiring'a connection with a party on a subscribers line terminating in the office Y,w1ll remove his receiver from its switchhook, and through the o eration ofthe line switch 100 will obtain a connection with the central oflice sender 105 over .the lower contacts of camslOl and 102, and

will in response to the-usual dial tone, dial the designation of the subscribers line desired. It will be assumed in this case, that the calling subscriber desires connection with the line and party whose designation is oaoillh dela ing setithe registers of the I officesender 105 to] register. the designation ofthe desired line, the sender 105 proceeds to set. the brushes of. district selector 15.0 and the brushes of office selector 175 upon the terminals of an idle trunk circuit extending to the office Y, in the manner fully forth in the aforesaid Patent No. 1,395,- 977, in accordance with the office designation of the office in which the'desired line terminates.

As soon as the ofiice selector 17 selects an idle trunk extending to the office Y, which will be'assumedto be the trunk disclosed, a i

circuit is established for line relay 2541 of the V trunk circuit which maybe traced from battery, left winding of rel e i, strap 25?, left armature and back-contact of relay 253 the upper left winding of repeating coil 251, the upper arn ati'u'eand back contact of relay 225, upper brushes of switches 17 5 and 150, lower contact of cam 103, through the controllingcircuits of sender 105, .over the lower contact of cam 1041, lowerhrushes of switches 150 and 175, innermost lower armature and backcontactfof relay 225, lower left winding of repeating coil 251, right armature and back contact of 'relay253', strap 258, to ground through the right winding. of relay 254:; Relayv 254: responds to current flowing inthis circuit. and establishes a circuit for relay 220 which may be traced from. battery through the outer right armature and con.-

i tact of relay 221, tl'1e' winding of relay 220,

, front contact inner right armature and back contact of relay 21 9 to ground at the armature and con:

tact offrelay254. Relay 220rupon' energizing, looks through its inner rlght armature and contact to. battery, at its outer right armature and front contactestablishes. the

previously traced circuit for assignment lamp 222 and; at itsinner left armature and prepares a circuit for the relay 223. I

1 Inr'esponse to the lighting of assignment lamp .222, theopcratordepresses key 217 --wherei 1-pon a circuit is established from hattery through the winding of relay 1'13, conductor. 11 i, strap 2 0 1, the lower armature and contact of relay; 224E, rigl'it windingof relay 223, inner left armature and contact of relay220, contact-ofzkey 21-7, strap 202, conductor 2 1-6, armature and back contact of: relay 11.5 to ground at theright armature and back contact of'relay 116.. Relays, 113 and energizein this circuit, relay locking from ground through its inner left armature and front contact-through both Of'iiS windings andithence to battery through-the winding of. relay 113 as previously tracechas soon as key2l7-isreleas'ech Relay 223 upon, energizin'g, closes an obvious circuit for relay-221 which in turn, operatesrelay 218 over the circuit previously described. Relay-218 upon energizlng, closes a locking circuitforitself extending from ground through its winding, front contact of its outer rightarma ture, to battery through the winding of relay, 219, relay 219, however, not ellerglzing at this time since its winding is shunted by battery connected through the inner, right armature and contact of relay 220.

lZVith relay energized, a circuit is. now. established for relay 225 which may betraced; from ground through the left. armature and back contact of relay 116, the

winding of relay 115, conductor 124, the

outer left armature and front contact of' relay 223, the'winding of relay. 225, to battery at the inner left" armature] and front Contact ofrel-ayf218. 'lVith relay 225 energized, the tip. and ring conductors 255. and 25.6'of the trunk circuit extending back to bank terminals of ofiice selector 175 are dis connected from. the windings of relay 254i and connected over straps 247 and 2 18. with conductors 117 and 118 eiitendingto the indicator. mechanism of 1. As soon as the windings of relay 25 1 are disconnected from the conductors ofth'e trunk circuit, relay 25st deenergizesl opening the locking circuit of relay 220, which in turn deenergizes removing the, shunt from around the winding of relay 219i Relay 219 now energizes in, thelocking circuit of relay 218. lVith relay. 220. deenergized and relay 221 energized, a circuit is established for flashing lam 222 as previousl 1 traced for 'iv- P L b ing the operator a signal that impulses are being received. from the distant sender for recording the deslgnatlon of the desired line upon the indicator mechanism which shehasconnected to the trunk circuit.

At the time. relay 225 operated to open the circuit extending through the windings of relay25 l hack to the office X, the sender 105'a dvances in, the, well known manner to 1 a position in which it commences the trans mission-of codefimpulses for recording the designation. ofthe desired line upon the indicator mechanism of Fig, 1. In accord-- ance withwell. known, practice, each code the second and fourth impulse-s being, either tures 01: control relays 11.9, 120v and'121. The circuit established by the operation of relay 225; over conductors 117 and 118 may now be traced 111 part from the sender105 through the lower contact of ear-r1103, upper brushes of switches 150' and 175- upper armature and front contactof relay 225. strap 248, conductor 1'18, winding of marginal control relay 119, windings of negatively polarized relay 120, windings of positively polarized relay 121, conductor 117, strap. 2 17, innermostlower armature and front contact of relay 225,- conductor 256, thence over the lower brushes of switches 175 and 150 and the lower contact of cam 10 1 to the sender 105.

For registering the party designationlV, the sender 105 transmits a code of two impulses comprising a strong-negative impulse followed by a weak negative impulse. In response to the firstimpulse'of strong negative, current, the negatively polarized relay 120 and the marginal relay 119 operate. Relay 120' upon' operating closes a circuit which may be-traced-froin ground on conductor 123 through the armature and contact of relay 120,; conductor 125, left armature and back contactof relay 126. left winding ofrelay 127 to battery through the left winding of relay 126. Relay 127 energz'izes but relay 126 does not receive sufiicient current to cause its energization. Upon the energization of relay 127, a locl inn circuit is established therefor, extendin from battery through the left winding of relay 126, lcftwinding of relay 127,

right winding f-relay 126, inner right armature andcontact of relay 127. to ground on conductor 123. Since at-this time. the right winding of relay126 is shunted by ground connected through'th'e ari'nature and contact of relay 120. relay 126-does not energize. \Vith relay 127 energized, a circuit is established for-switching relay 128 which may be traced from battery through the winding of relay 128. right armature and back contact of switching relay 129'. outer right arn'iature and front contact of-relay 127 to ground on conductor 123. Relay 128 now locks through its windin of relay 129, the rightarmature and contact of relay 128 to ground on conductor 123. Relay 129,how-ever-,- does notenergize in this locking circuit-since its winding is shunted by ground connected through the outer right armature and contact-of relay 127.

'lelay 119upon energizingestahlishes a circuit from ground on conductor 12 through the armatureand contact of relay 1.19. conductor 1S0.the outer right armature and backpontact of relay 126. the outer left armature and back contact of relay 129, upper winding offst-ations register relay 108 to battery. Relay 108,'upon energizing, looks from battery throughlooth of its windings and its innermost lower armature and contact to ground on conductor123, lVhen the first impulse ofthestations-code terg', the winding: I

minates, relays 119 and 120 deenergize, relay 120 removing the shunt from around the right winding! of relay 126 permitting this relay to energize in the locking circuit of relay 127. Relay 126 at its inner right armature and contact now closes a further shunt around the winding of switching relay 129.

In response to the second impulse of weak negative current. negatively polarized'rclay 120 energizesnclosing a circuitextendine from ground on conductor 123 through the armature and contact of relay 120, conductor 125, the left armature and front contact of relay 126, to battery through the left winding oi relay 126. Relay 126 is maintained 8111. lZ(1 over this circuit but relay 127 is shunted and deenergizes. impulse ceases, relay 120 deenergizes, unlocking relay 126. Since both relays 126 and 127 are now deenergized, the shunts previously n'rentioned extending about the winding of relay 129 are opened, and relay 129 energizes in the locking circuit of relay 128.

The remaining codes of impulses are now received in the usual manner in accordance with the thousands, hundreds, tens and units digits of the desired'linedesignation, a pair of switching relays such as 131, 132- and 133. 134. operating in response'to eachcode of impulses transmitted. until upon the con:- pletion of the transmission of the unitscode. switching relays 185 and 136 become operated and locked. This operation is in ac cordance with the disclosure of Patent No.

lei-64,0841 hereinbeforc referred to. lVhen relay 136 operates, anobvious circu t is closed for relay 11.6, which opens the circuit previously traced through the windings of relays 115' and 225c'ausing theirrelease. A circuit is also closed for lighting the lamps of the indicator for displaying the complete line designation. The circuit for the lV stations lamp 137 may be traced "fron'i battery through? the right armature andv contact of switching relay 13", lamp 137, the innermost upper armature and back. contact of stations register relay 109, to ground through the lowermost armature and con tact of stations register relay 108. y

The conductors 138 and 139 are connected to ground at contacts of the stations register relays for operating the ringing current selection relays 229 and 230 of the trunk circuit in the following manner: The circuit for relay 230 may be traced "from battery through the ii inding of relay 230. lowermost armature and front cont-act of relay 225, strap 201, conductor 139, the lower armature and back contactof relay 110', the;

innermost upper armature and front contact of relay S, the upper armatures and baolr contacts of relays 107 and 106to the ground at the leftarmature and front contact of switching relay- VVhen the 133, The circuit for relay 229 may be traced from battery lays 229 and 230 are energized and locked over their inner left armatures and front contacts to ground at the make contacts of the outer left armature of relay 219, during the transmissiono'f the hundreds code of impulses and therefore, ringing current selection is accomplished before relay 225 deenergizes following the operation of'units switching relay 136. I

Upon the deenergization of relay 225, the control conductors 117 and 118 extending from the indicator mechanism of Fig 1 to the sender 105 are disconnected, the sender is thereupon released from connection withthe established connection and a talkingcircuit' is established over the upper contacts of cams 101 to 104 inclusive, in the well known manner. As soon as this talking circuit is established, line relay 254 again energizes, closing a-circuit from ground at its armature and front contact through the inner right armature and front contact of relay 219 through the winding of relay 219 to battery for maintaining this relay energized and for shunting down relay 218. Relay 218 thereupon deenergizes.

The operator, noting the display of the line designation inserts plug 231 into jack 232 whereupon relay 224 energizes, opening the circuit of lamp 222 and the holding circuit of relays 113 and 223. Relay 113 now deenergizes removing ground from the holding conductor 123 thereby releasing all apparatus of the indicator. A circuit is now closed for the ringing lamp 236 which may be traced from ground through the interrupter 226, the right armature and front contact of relay 230, lamp 236, left arma ture and back contact of relay 237 to battery through the intermediate armature and front contact of rclay224. The lamp 236 is thereupon flashed to indicate to the operator that she should throw the ringing key 234 in accordance with the code necessary to ring either the'party W or the party M on the line whose designation is displayed by the indicator. When the operator throws the key 234, the circuit for applying ringing current is established as hereinbefore described.

249 and 253 operate as hereinbefore described and relay 237 energizes to open the circuit of lamp 236. Relay 253, upon oper-- ating,reverses the battery and ground con nections from the windings of relay 254- to the conductors of the trunk circuit for supervisory purposes. Upon the termina- When the called subscriber responds to the ringing current, relays 239,

'tion of the conversatiomwhen subscriber A toa party W of a party line; If it is desiredto signal the party R, either the party It key of the master keys 250 or the stations register relays 108 and 109 of the indicator will be operated and ringing selection relay 229 will be energized, relay 230 not being operated. lVhen, therefore, the circuit for ringing lamp 236 is established, the lamp will glow steadily since the armature of re lay 230 is connected atits'back contact di rectly to ground rather than through the interrupter 226. The operator will then operate the ringing key 234 to apply ringing current to the called line in a manner to apply ringing current distinctively to bells of substations B and D. It may, for

example, be assumed that the subscriber at substation D will respond when his bell rings with a single long ring.

To signal the partyJ, the J key ofthe master ringing keys 250 or the stations register relay 107 is. operated 'whereupon neither relays 229 nor 230 are operated and consequently current from the source 241 is applied to the ring conductor 244 of the called line and the ringing lamp 236 is lighted steadily to indicate that the ringing key 234should be operated to ring the bells of substations C and E with a single long ring. the master keys 250 or the stations register relay 106 is operated whereupon relay 230 vis operated, relay 229 being 'unoperated.

With only relay 230 operated, ringing current from source 241 is applied to the ring conductor 244 of the called line and the ringing lamp is flashed to indicate that the ringing key 234-should be operated to ring the bells of substations C and E withi'two long rings. v i I What is claimed is:

1. In a telephone exchange system, an incoming line, an outgoing line, a plurality of substations connected to said outgoing line, a signal associated witheach of said substations, means for interconnecting said lines, a source of signaling current, means cont-rolled over said incoming linefor selec-- tively associating said source of current with said outgoing line, a signaling device for indicating the manner in which said source of current should be applied to said outgoing line, and manually operated means To ring the party M, the M key of fit) for applying saidcurrent'in accordance with said indication.

2. In a telephone exchange system, an inc( n'iin "li1ie, an outgoingline, a plurality of substations connected to said outgoing line, a signal associated with eachoif said'substations, the signals of certain of said substations being responsive to signaling current applied to one side'of said line and the signals of the remaining substations being responsive to signaling current applied to the other side of said line, means for interconnecting saidlines, a source of signaling current, means controlled over said incoming "line for associating saidsource With either side of said outgoing line, a'signaling device for indicating the/manner in Which current tromsaid source shouldbe applied to said outgoing line, and manual means tor applying said current in "accordance with said indications.

In a telephOne eXchange system, an incoming line, 'an outgoing line, a plurality oi substations connected to said outgoing line, a signal-associated with e'ach-oit'said substations, the signals of certain of said substations being responsive to signaling current-applied tooneside off-said line and the signals the remaining substations being responsive to signaling current applied to the 'ot-her'si-de of said line, means for interconnecting said lines, a source of signaling current, means controlled over said incoming line for associating said source of current with either side of said outgoing line, a key for distinctively applying said source of current, and a signaling device for indicating the distinctive manner in which said current should be applied.

at. In a telephone exchange system, an incoming line, an outgoing line, a plurality of substations connected to said outgoing lines, a signal associated with each of said substations, the signals of certain of said substations being responsive to signaling current applied to oneside of said line and the signals of the remaining substations being responsive to signaling current applied to the other side of said line, means for interconnecting said lines, a source of signaling current, substation selecting means, means controlled thereby for associating said source of current with either side of said line, a key for distinctively applying said source o-if current, and a signaling device controlled by said substation selecting means for indicating the distinctive manner in which current from said source should be applied.

5. In a telephone exchange system, an incoming line, an outgoing line, a plurality of substations connected to said outgoing line, a signal associated with each of said substations, means for interconnecting said lines, a source of signaling current, substation selecting means, manually operable means for applying current from said source to said outgoing line for operating .said signals in a distinctive manner, and means controlled by' said substation selecting means for indicating the distinctive manner in which said signaling current should be applied. v I

6. In a telephone exchange system, an incoming line, an outgoing line, a plurality oi substations connected to said outgoing line, a signal associatedwith each of said substations, means 1 for interconnecting said lines, a source of signaling current, substation selecting means, means for applying current from said source to said outgoing line for operatingv said signals in a distin'ctive manner, a lamp signal, and means under the control of said substation selecting means for lighting said lamp signal in a distinctive mann'er'for indicating the distinc'tiv'ean'anner in which said signaling current shouldbe applied.

7-. In a telephone exchange system, an incominglinaan outgoing line, a plurality of substations connected to said outgoing 'line,a signal associated with each of'said su tions, the signals of certain of said substations being responsive to signaling current applied "toone side of said line and the signals oi the remaining substations being responsive to current applied to the other side of said line, means for interconnecting said lines, a source of signaling eurrent,su'bstation selecting means, a signaling device, a key for applying current from said source to said oi'ltgoing'line, and a pair of relays controlled selectively by said selecting means, one of said relays determi'ningto which side otsaid line said source of current shall be applied andthe otherot said relays operating said'signaling device to in.- dicate the distinctive manner in Which current from said source shall be applied.

8. In a telephone exchange system, an op-' erators position, a trunk circuit incoming thereto, an indicating device at said position, means operated over said trunk circuit for setting the indicating device in accordance with the designations of desired lines,

an outgoing line, a plurality of substations,

on said outgoing line, a signal associated With each of said substations, means at said position for interconnecting said trunk circuit and said line, a source of signaling current, manually operable means for applying current from said source to said outgoing line for operating said signals in a distinctive manner, andv means controlled by said indicating device in accordance with the stations setting thereof for indicating to the operator the distinctive manner in Which said signaling current should be applied.

9. In a telephone exchange system, an operators position, a trunk circuit incoming Ill.)

thereto, anlindicating device at said operator7s position, means operated over said trunk circuit for settingthe indicating de vice in accordance with the designations of desired lines, an outgoing line, a plurality of substations on said outgoing line, a signal associated with each of said substations, the signals of certain of said substations being responsive to signal current applied to one side of said line, and the signals'of the remaining substations being responsive to signaling current applied to the other side of I said line, means at said position for interconnecting said trunk circuit and said line, a source or signaling current,a signaling device, manual means for applying current from said source to said line, and a pair of relays controlled selectively by said indicatingdevice in accordance with the stations setting thereoflone of said relays determining to which side of the line said source shall be applied and the other of said relays operating said signaling device to indicate the distinctive manner in which current from said source, shall be applied by said manual means.

10. In a telephone exchange system, an incoming line, an outgoing line, aplurality of substations connected to said, outgoing line, a signal vassociated with each of said substations, means for interconnecting said lines, asource of signaling current, station selecting keys for normal association with said interconnecting means, an indicating said indicating device for indicating thedistinctive manner inwhich signaling currentshould be applie 11. In a telephone exchange system, an incoming line, an outgoing'line, a plurality of substations connected to said outgoing line, a signal associated with each ofsaid substations, means for interconnecting-said lines, a source of signaling current, means controlled over said incoming line for selectively associating said source ofcurrent Withsaid outgoing line, and manually operated means for applying said current in accordance with specified ringing codes.

In witness whereof, I hereunto subscribe my name this29th day of December 1).,-

j JACK F. DAHL. 

